Question

Угадайте корень уравнения x(x+8)=105

Answer 1

$x^{2}+8x=105 \ x^{2}+8x-105=0 \ D=8^{2}-4*(-105)*1=64+420=484=22^{2}\ x_{1}= frac{-8-22}{2}= frac{-30}{2}=-15\ x_{2}= frac{-8+22}{2}= frac{14}{2}=7$

Answer 2

x(x+8)=105
x^2+8x=105
x=7
7(7+8)=49+56=105